A hockey player who excels at committing cheap shots and not being called for a penalty. Most hockey ninjas, if caught by a player, will use their art to disappear behind a referee, thereby escaping any retribution.
Fan 1: "How did Darcy Tucker not get called for boarding?!"
Fan 2: "Because he is a hockey ninja."
A hockey player who's inconspicuous presence causes the opposing team to pay him/her little attention only to appear out of thin air and score. Hockey Ninjas are sneaky, sly, and skillful; striking with incredible speed and accuracy.
"Oh my gawd! He came out of nowhere and scored?"
"That's because... he's a Hockey Ninja!"